The invention relates to external pinion type odometers, and more particularly to an external pinion type odometer in which digit wheels are arranged close to one another.
Conventionally, external pinion type odometers of this type are used as, e.g., an odometer attached to a vehicle to measure the distance traversed or as being incorporated into a combination meter together with other types of measuring instruments for the vehicle.
Vehicles, with recent improvements in their performance, can run for more than 100,000 km. Under such circumstances, an odometer capable of indicating the travelling distance in 6 digits is under study in order to replace the 5-digit indication system of a conventional odometer whose maximum count of distance is generally 99,999 km. If the number of digits is increased using the conventional construction, the space to indicate the travelling distance must be increased or a like problem must be handled, and these problems are taken care of by arranging the digit wheels close to one another.
FIG. 3 is a plan view showing an exemplary conventional odometer in which its digit wheels are short-distanced from one another. In FIG. 3, a rotating shaft 2, whose ends are firmly fixed to two confronting supporting plates 1a, 1b of a frame 1, rotatably supports a group of digit wheels 3, the group allowing indications in 6 digits. Each of the digit wheels 3 has numbers 3', 1 through 0, stamped equidistantly all around its surface 3a by, e.g., hot stamping or printing. Further, as shown by a partially enlarged view in FIG. 4, each lower digit wheel 3 has a recess 3b formed on its left edge so that the recess 3b extends beyond the stamping width of a recessed number 3', whereby two drive gears 3b' are formed integrally with the corresponding digit wheel 3. Each upper digit wheel 3 has on its right side a driven gear 3c consisting of twenty (20) teeth, the driven gear being formed integrally with the corresponding digit wheel 3.
Reference numeral 4 designates a drive wheel having no character stamped on its surface and only two drive gears (not shown) are formed on its left side. The drive wheel 4 is driven by a not shown means in accordance with the driving of a vehicle.
A rotating shaft 5, whose ends are secured to two confronting standing strips 1c, 1d of the frame 1 and which is juxtaposed with respect to the rotating shaft 2, rotatably supports six (6) transfer pinions 6. The six transfer pinions 6 are arranged so that each alternates with one of seven wheels consisting of the digit wheels 3 and the drive wheel 4. As shown in FIGS. 5 and 6, each transfer pinion 6 has an array of eight (8) teeth. The array consists of four wide teeth 6a and four narrow teeth 6b, and each wide tooth alternates with each narrow tooth, all being flush with one reference side. It is so arranged that a narrow tooth 6b of the transfer pinion 6 is meshed with the driven gear 3c of each upper digit wheel 3 at all times, and that a wide tooth 6a is brought into engagement with the drive gears 3b' upon being inserted into the recess 3b as a result of each lower digit wheel 3 having made one full rotation and reached a predetermined rotating position. Accordingly, as the two drive gears 3b' have engaged with the wide tooth 6a of the transfer pinion 6 by one full rotation of the lower digit wheel 3 and the transfer pinion 6 thereby makes a quarter rotation, the narrow tooth 6b makes a rotating movement corresponding to two teeth. As a result, the corresponding upper digit wheel 3 having the driven gear 3c that is in engagement with the narrow tooth 6b at all times makes a 1/10 rotation, setting a next number to a next indicating position.
As described above, to indicate a greater number of digits with the conventional odometer, a limited space is utilized in such a manner that the digit wheels 3 are distanced close to one another by forming the two drive gears 3b' integrally with each digit wheel 3 while arranging on the left side of the digit wheel 3 the recess 3b so that the recess 3b extends beyond the stamping width of the recessed number 3'. For this reason, when a digit wheel 3 is rotating without engagement of a wide tooth 6a of the corresponding transfer pinion 6 with the drive gears 3b', the surface 3a of the digit wheel 3 is rubbed by the wide tooth 6a of the transfer pinion 6 as shown in FIG. 4. This also causes the number 3' portion, which is indicated by shading in FIG. 4, to be rubbed by the wide tooth 6a, and, as a result, the stamped portions of the lower digit wheels which rotate more frequently than the upper digit wheels come to peel off.
The invention has been made in view of the above circumstances. Accordingly, an object of the invention is to provide an external pinion type odometer in which the stamped numbers do not peel off even if the recess to be engaged with a wide tooth of the transfer pinion extends beyond the stamping width of a number so that the digit wheels can be arranged close to one another.